1. Field of the Invention
The present invention relates to a fuel cell stack as a stack body formed by stacking a plurality of unit cells.
2. Description of the Related Art
A fuel cell includes a unit cell formed by sandwiching a membrane electrode assembly between a pair of separators. The membrane electrode assembly includes an anode, a cathode, and an electrolyte (e.g., solid polymer electrolyte membrane or oxide ion conductor) interposed between the anode and the cathode. Normally, a plurality of the unit cells are stacked together to form a fuel cell stack. In general, in the fuel cell stack, a tightening member is provided for applying a tightening load to components between a unit cell positioned at one end and a unit cell positioned at the other end for preventing detachment of any of the unit cells.
Impact loads from the outside may be applied to the fuel cell stack of this type. As described above, the tightening load is applied to the unit cells in the stacking direction by the tightening member. Therefore, the unit cells do not move easily in the stacking direction. However, as for directions perpendicular to the stacking direction (height and horizontal directions), since no tightening load is applied, the unit cells move easily.
As a possible approach to avoid such movement, a load receiver may be provided in the outer end of the separator to absorb the impact load by the load receiver. For example, in Japanese Laid-Open Patent Publication No. 2008-027761, the applicant of the present invention proposes structure in which a fuel cell stack is placed in a casing, and load receivers provided in predetermined separators protrude to contact the inner wall of the casing.